This invention relates generally to apparatus for heating a fluid-control device disposed in a conduit at a well site and more particularly, but not by way of limitation, to apparatus for insulating and heating a gas regulator mechanism known as a "Little Joe."
Various valves and regulator devices are found at oil and gas well sites. Because the fluids flowing through these devices contain liquids which can freeze and render the devices inoperable, it is important that some means for keeping the devices from freezing or for thawing them when they become frozen be provided. For example, it is known in the art that gas regulators known as "Little Joes" can freeze whereby the gas regulation function is not provided. To thaw these frozen gas regulators, the prescribed maintenance procedure is to disassemble the regulator and remove the ice plug which is formed; however, in actual practice a short-cut is frequently taken whereby ignited gasoline-soaked rags or flaming torches are applied directly to the frozen device to thaw it. These techniques utilizing flaming rags or torches are extremely dangerous techniques because there is no accurate control of the heat applied to the device. This can create an explosion due to the increased pressure differentials created within the device by the inadequately controlled high heat. This opportunity for explosion is enhanced in a "Little Joe" because of the possibility of a worn gasket which seals an aperture opening to the atmosphere for atmospheric pressure control and because of a faulty casting which can occur in some of these devices due to the effects of freezing.
Therefore, there is the need for an insulated apparatus to control the heating applied to a device at a well site to prevent it from freezing or, if frozen, to safely thaw it. To insure adequate control, the heating mechanism within the apparatus should be electrically energized from a source including a primary power supply and a reserve power supply to insure continued operability in the remote locations at which well sites are often found. These power sources should be efficient to reduce the cost of their operation. The heating mechanism should also be maintained in an insulated housing to protect the device from the environment and to assist in the insulation feature of such a needed apparatus.